well...i asked that same question....the guy told me to wedge your fingers under the back of the speaker box and pull...it SHOULD come off...but i havent tried it...
You cannot just wedge your fingers under the speakers or the rear deck and pull, unless you want to destroy the rear deck, as it is only made of cardboard. The bottom seats lift up and out with a little effort. You then have to take a socket and remove the rear seat back. Pry the seats away at the side with your hand a little bit and down in there you will see the bolt head. There is one on each side of the seat back.
After you get that seat back out of there you will see that you can access the speakers by lifting up the deck lid.
I agree, you have to remove the entire rear deck to get the speakers out. I just did this this past weekend. I had the luxury of folding my back seats down instead of removing the seatbacks.
I agree, don't try to pry off the speaker cover, as others have said. I had to replace a speaker my self. 1) Pry off the bottom seat bench, it's clipped in so it should pop off. 2) Useing correct wrench or rachet undo the 3 or 4 bolts securing the backing of seat and remove it from car. 3) Pop the covering to break light in rear window off, should be 2 little pins holding it on, and remove light bult from covering. (may or may not need to do this. 4) In the trunk of car you'll need to push several pins up that fastens the rear deck down out.
You should then be able to get at the speakers.